Diving Deeper Shorts: Episode 10 (March 10, 2011) - Eutrophication

HOST: Today on Diving Deeper Shorts, we revisit our first Diving Deeper interview on eutrophication from January 2009 with Dr. Suzanne Bricker from the National Centers for Coastal Ocean Science.

Let’s listen in.

HOST: First, can you explain to us a little bit more about the difference between eutrophication and nutrient pollution?

SUZANNE BRICKER: Essentially, eutrophication and nutrient pollution are the same thing. Nitrogen and phosphorus are nutrients that plants need to grow. The problem occurs when an excess amount of these nutrients are delivered to a water body and that causes an excessive growth of algae that clouds the water. This may cause other more serious problems such as low levels of dissolved oxygen as the algae decomposes.

HOST: Ok, so what can cause these increased levels of nutrients and where do nutrients come from?

SUZANNE BRICKER: Nutrients come from a variety of different sources. They can occur naturally, and always have, as a result of weathering of rocks and soil in the watershed and they can also come from the ocean due to mixing of water currents.
But, we are most interested in the nutrients that are related to people living on and in the coastal zone because human-related impacts are much greater than natural inputs.

Basically, more people living in the coastal zone means more nutrients entering our coastal waters from wastewater treatment facilities, runoff from land in urban areas during rains and from farming. When fertilizers are applied to crops, the excess nutrients that aren’t taken up by the plants wash away in runoff typically during a rain storm. This also happens in urban areas where lawn fertilizers are used and, interestingly, pet and wildlife wastes can also be a nutrient source.

I should also mention here that it’s not just the coastal zone, but upstream sources that can impact water bodies. And so, it’s important not only to focus on the coastal zone, but also those upstream sources of nutrients as well.

HOST: Can eutrophication happen anywhere or only in coastal areas where there is runoff?

SUZANNE BRICKER: Actually, eutrophication can happen anywhere. It can happen in lakes, streams, or estuaries - basically any body of water where nutrients can enter. We mostly work in estuaries or bays, which is where rivers meet the sea. Estuaries are of particular interest to us because of our interest in using them, for instance, for recreational and commercial fishing. These are supported because estuaries are typically full of fish populations. And since eutrophication can cause low dissolved oxygen which kills fish, fisheries are in danger from nutrient pollution.

That’s all for today’s Diving Deeper Shorts, where we highlight a few minutes of your favorite Diving Deeper episodes.

Want to learn more? Go to oceanservice.noaa.gov/podcast.html and select the January 2009 podcast archive to listen to the full interview with Suzanne on eutrophication.